1. Field of the Invention
The present invention relates to a method of improving the surface hydrophilic property of a copper or copper alloy made heat-transfer tube which is formed in a specified tube shape and is used for heat exchangers, and particularly to a method of applying a surface hydrophilic treatment on the surface of a metal heat-transfer tube by plasma discharge or corona discharge.
2. Description of the Related Art
Methods of improving the surface hydrophilic property of a metal heat-transfer tube used for heat exchangers have been known as follows: